2010
2010
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Record 121 of
Title:Cubic sinusoidal phase mask: Another choice to extend the depth of field of incoherent imaging system
Author(s):Zhao, Hui(1); Li, Yingcai(1); Feng, Huajun(2); Xu, Zhihai(2); Li, Qi(2)Source: Optics and Laser Technology Volume: 42 Issue: 4 DOI: 10.1016/j.optlastec.2009.10.004 Published: June 2010Abstract:Wave-front coding is a well known technique used to extend the depth of field of incoherent imaging system. The core of this technique lies in the design of suitable phase masks, among which the most important one is the cubic phase mask suggested by Dowski and Cathey (1995) [1]. In this paper, we propose a new type called cubic sinusoidal phase mask which is generated by combing the cubic one and another component having the sinusoidal form. Numerical evaluations and real experimental results demonstrate that the composite phase mask is superior to the original cubic phase mask with parameters optimized and provides another choice to achieve the goal of depth extension. ? 2009 Elsevier Ltd. All rights reserved.Accession Number: 20100112614124 -
Record 122 of
Title:Optical design of the uncoaxial three-mirror system with wide field of view
Author(s):Guo, Yongxiang(1,2); Li, Yingcai(1); Liang, Tianmei(3); Chen, Qinfang(1,2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 30 Issue: 9 DOI: 10.3788/AOS20103009.2680 Published: September 2010Abstract:Based on the theory of off-axis three-mirror ststem, an optical system with effective focal length of 5000 mm and field of view of 5° is designed. The image qualities of this system are near diffraction limit. Some factors in practical engineering application are taken into account in course of design, so that this system is very useful in the field of space optical remote sensing.Accession Number: 20104313323596 -
Record 123 of
Title:Multispectral images compression based on JPEG2000
Author(s):Wei, Junxia(1,2); Wei, Ruyi(1,2); Gao, Xiaohui(1,2); Duan, Xiaofeng(1)Source: 2nd International Conference on Information Engineering and Computer Science - Proceedings, ICIECS 2010 Volume: Issue: DOI: 10.1109/ICIECS.2010.5677876 Published: 2010Abstract:Multispectral image compression which are based on the one-, two- and three-dimensional wavelet transforms has been existed in many papers. Existing image compression algorithms have proved to be very efficient in compressing these kinds of images. We adopted the principal component analysis , clustering and spectral angle cosine to classify and compress in spectral dimension. In this article, we present lossy compression based wavelet; the information loss is measured by Peak-Signal-to-Noise Ratio (PSNR). We introduce the spatial compression based on JPEG2000 and improved embedded zerotree (EZW) encoding. We use the different compression rate to compress image, when the compression rate is 10:1, subjective value and object value is optimal. Not only the single band, but also the composing image, the spectral curve is nearly same. ?2010 IEEE.Accession Number: 20110813673686 -
Record 124 of
Title:Reserch on the automatic stitching of panorama camera image based on system similarity matching principle
Author(s):He, Jianwei(1,2); Yang, Jianfeng(1); Xue, Bin(1); Chen, Xiao(1,2); Yan, Peipei(1,2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 30 Issue: 4 DOI: 10.3788/AOS20103004.0989 Published: April 2010Abstract:The image stitching based on feature point is not only invulnerable to the light, rotation and other factors, but also helpful to increase efficiency. It has become one of the most attended methods. Scale invariant feature transform (SIFT) is a better coner extraction algorithm, but there are still some problems in the matching step. A new matching principle based on system similarity theory was proposed, and then it was compared with the traditional matching principle. The problems with tradtional matching principle was pointed out, and also the precision and speed of the new principle was tested , and the reason why the new principle get higher precision was analysed. By the new principle the matching features were detected successfully. And then, the transform matrix was calculated by the progressive sample consistency algorithm. Further more, it was optimized by the Levenberg-Marquardt (L-M) algorithm, and finally automatic image stitching was realized. At last, the stiching result of panorama camera image was given, further discussion about the new matching principle was also given in the end of the paper.Accession Number: 20102112958549 -
Record 125 of
Title:A first-principles study of the size-dependent electronic properties of SiC nanotubes
Author(s):Zhang, Weihu(1,2,3); Zhang, Fuchun(3); Zhang, Zhiyong(4); Lu, Shuyuan(5); Yang, Yanning(3)Source: Science China: Physics, Mechanics and Astronomy Volume: 53 Issue: 7 DOI: 10.1007/s11433-010-4029-7 Published: July 2010Abstract:We investigate the structural and electronic properties of SiC nanotubes (NTs) with hexagonal cross sections by a first-principles calculation using plane-wave ultra-soft pseudo-potential technology based on the density-functional theory. Our results reveal that surface-layer C and Si atoms relax significantly upon decreasing the tube-wall thickness because of surface-size and quantum-size effects. We also find that all relaxed SiC NTs stay stably on the nanoscale because of an admixture of sp2 and sp3 hybridization between C and Si atoms and a strong covalent, and that the band gap tends to decrease with increasing tube-wall thickness. Our calculations further indicate that both C and Si atoms on the inner and outer surface of SiC NTs contribute to defect states at the top of the valence band and at the bottom of the conduction band. These results provide reference information for a thorough understanding of the properties of SiC nanostructures and also enable more precise monitoring and control of the growth of SiC nanostructures. ? 2010 Science China Press and Springer-Verlag Berlin Heidelberg.Accession Number: 20103313154123 -
Record 126 of
Title:A review of motion estimation algorithms for video compression
Author(s):Xie, Liyin(1,2); Su, Xiuqin(1,2); Zhang, Shun(1,2)Source: ICCASM 2010 - 2010 International Conference on Computer Application and System Modeling, Proceedings Volume: 2 Issue: DOI: 10.1109/ICCASM.2010.5620542 Published: 2010Abstract:The key to high performance of video compression lies in an efficient reduction of the temporal redundancy. For this purpose, the block-based motion estimation (BBME) technique has been successfully applied in the video compression standards from H.261 to H.264. The most straightforward BBME method must be full search algorithm (FSA) that searches every candidate position within the search range. Since FS consumes extremely high computational cost, development and refinement on ME algorithms have been fueled to archive better tradeoff between the computational cost and the ME speed. In this paper, we study the low complexity ME algorithms and classify them into three categories, namely modeling the matching error surface, fast full search and reduction of searching candidate points. In the following sections, we will have a brief review across all these categories. The aim of this review is to provide the succeeding researchers with some constructive information in design of the fast ME algorithms. ? 2010 IEEE.Accession Number: 20104913451952 -
Record 127 of
Title:Outfield calibration analysis of spatially modulated imaging fourier transform spectrometer
Author(s):Gao, Jing(1,2); Ji, Zhongying(1); Cui, Yan(2); Wang, Zhonghou(1); Shi, Dalian(1,2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 30 Issue: 5 DOI: 10.3788/AOS20103005.1321 Published: May 2010Abstract:Spatially modulated imaging Fourier transform spectrometer (SMIFTS) is an instrument that depended on interference, it can obtain interferential information and achieve spectral information by Fourier transform. The lamp-house of outdoor calibration is sun, which can offset effective lamp-house of laboratory calibration (sun simulation)'s disadvantage of low shortwave radiation and signal to noise ratio (SNR), also simulate sun reflection spectrum speciality availably of SMIFTS object, obtained interferential information exactly, result of laboratory radiation calibration is validated. Principle, method and result of the experiment are shown, used sun-aerosphere-diffuse reflection method and standard-radiation-transfer method to accomplish outfield calibration in Dali. The results indicated that the uncertainty of sun-aerosphere-diffuse reflection method is 6.3%, uncertainty of sun-aerosphere-diffuse reflection method is 6.0%.Accession Number: 20102413003392 -
Record 128 of
Title:Global motion compensation for image sequences and motion object detection
Author(s):Zhang, Shun(1,2,3); Su, Xiuqin(1,2,3); Xie, Liyin(1,2,3)Source: ICCASM 2010 - 2010 International Conference on Computer Application and System Modeling, Proceedings Volume: 1 Issue: DOI: 10.1109/ICCASM.2010.5620430 Published: 2010Abstract:A effective approach to global motion compensation and moving object extraction is proposed. Firstly, feature-block detection and search-matching algorithm are used to attain background motion vectors of global image. Then, once the global motion vectors are robustly estimated, relatively stationary background can be almost completely eliminated through the registration difference algorithm. Finally, higher-order statistics is used to attain the motion target exactly. The experimental results validate that the proposed algorithm improves the performance of detection moving targets and effectively restrains the noise disturbance. ? 2010 IEEE.Accession Number: 20104913451818 -
Record 129 of
Title:Design of servo control mechanism for laser tracking detection system
Author(s):Qiao, Yongming(1,2); Lian, Xuezheng(1,2); Wang, Yaohui(1,2)Source: 2010 International Conference on E-Product E-Service and E-Entertainment, ICEEE2010 Volume: Issue: DOI: 10.1109/ICEEE.2010.5661603 Published: 2010Abstract:A servo control system based on DSP+FPGA structure was proposed in this paper in order to achieve better performances of laser tracking system, meanwhile principles of position detection were introduced in details and the modeling as well as simulation for this system was built. FPGA was implemented in this system to sample the signals from detectors and calculate the values of position and velocity from photoelectric encoder. The control algorithm was accomplished by DSP finally. The experimental results show high tracking accuracy, strong ability of anti-interference and fast response. ?2010 IEEE.Accession Number: 20110313605208 -
Record 130 of
Title:Electronic structure and magnetism of Fe-doped SiC nanotubes
Author(s):Zhang, Weihu(1,2,3); Zhang, Fuchun(3); Zhang, Zhiyong(4); Lu, Shuyuan(5); Yang, Yanning(3)Source: Science China: Physics, Mechanics and Astronomy Volume: 53 Issue: 9 DOI: 10.1007/s11433-010-4089-8 Published: September 2010Abstract:The electronic structure and magnetic properties of Fe-doped SiC nanotubes are investigated by using the first-principles method based on density functional theory (DFT) in the local spin density approximation (LSDA). The calculation results indicate that the SiC nanotube of Fe substitution for C exhibits antiferromagnetism while ferromagnetism features prominently when Fe substitutes Si. This is a kind of half-metal magnetic material. The formation energy calculation results show that the formation energy of ferromagnetic structure is 3.2 eV lower than that of antiferromagnetic structure. Fe atoms are more likely to replace Si atoms. Spin-orbit coupling induces electron spin polarization in the ground state. Also, the doping Fe atoms make relaxation towards the outside of the tube to some extent and larger geometric distortion occurs when Fe substitutes C, but the whole geometric structure of SiC nanotubes is not damaged due to the doping. It is revealed in the calculation of energy band structure and density of states that more dispersed distribution of energy levels is produced near the Fermi level. For Fe substitution for Si, obviously there are spin-split and intense p-d hybrid effects by Si 3p electron spins and Fe 3d electron spins localized at the exchanging interactions between magnetic transitional metal (TM) impurities. Spin electronic density results indicate that system magnetic moments are mainly generated by the unpaired 3d electrons of Fe atoms. All these results show that the transition metal doping SiC nanotube could be a potential route to fabricating the promising magnetic materials. ? 2010 Science China Press and Springer-Verlag Berlin Heidelberg.Accession Number: 20103313154180 -
Record 131 of
Title:Image denoising via doubly Wiener filtering with adaptive directional windows and mean shift algorithm in wavelet domain
Author(s):Li, Xiang(1,2); Su, Xiuqin(1); Ji, Lei(1,2)Source: 2010 IEEE International Conference on Mechatronics and Automation, ICMA 2010 Volume: Issue: DOI: 10.1109/ICMA.2010.5588478 Published: 2010Abstract:An image is often corrupted by noise in its acquisition or transmission. The goal of denoising is to remove the noise while retaining as much as possible the important signal features. In this paper, we propose a doubly local Wiener filtering method using adaptive directional windows and Mean Shift algorithm, in which the Mean Shift algorithm is first used to naturally segment the image into regions of similar content, and then the adaptive directional windows which can change shape according to the different regions, are used to estimate the signal variances of noisy wavelet, finally the doubly local Wiener filtering is used to denoise the observed image. Simulations demonstrate this method substantially outperforms the original algorithm. ? 2010 IEEE.Accession Number: 20104813423652 -
Record 132 of
Title:Experimental research on image motion measurement using optical joint transform correlator for space camera application
Author(s):Zhao, Hui(1); Yi, Hongwei(1); Li, Yingcai(1); Che, Chicheng(2); Xiao, Xiao(3)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 7830 Issue: DOI: 10.1117/12.864658 Published: 2010Abstract:The optical joint transform correlator (JTC) is an effective way to measure the image motion that is hard to be eliminated for space camera. In this manuscript, the principle of JTC is briefly introduced and then a static experiment is designed to demonstrate the suitability of JTC for space camera application. The results demonstrate that the RMS (root-mean-square) error of motion determination can be controlled below 0.15 pixels in both the horizontal and vertical direction, which is good enough to satisfy the space camera requirements. Besides that, the performance of two methods used to locate the cross-correlation peak is also evaluated. Compared with the traditional centroid computing method, Intensity Weighting Centroiding (IWC) is superior because it can not only reduce the sensitiveness of cross-correlation peak to window size selection, but also improves measurement accuracy. ? 2010 Copyright SPIE - The International Society for Optical Engineering.Accession Number: 20104913464898